Age-specific electroencephalography dynamics during anesthesia: monitoring and neurocognitive implications.

Electroencephalography (EEG) reflects thalamocortical activity during anesthesia, but its signatures vary markedly with age. Alpha oscillations emerge in late infancy, peak in childhood, and decline with aging, producing substantial bias in processed EEG (pEEG) indices derived mainly from adult data. This narrative review summarizes age-specific EEG dynamics under γ-aminobutyric acid (GABA)-ergic anesthesia, highlighting developmental and aging trajectories, age effects on pEEG reliability, and associations with postoperative delirium (POD), emergence agitation (EA), and recovery outcomes. In infants and toddlers, immature alpha activity may lead to less reliable or incompletely suppressed index values even during deep anesthesia, whereas in children up to 6-7 years, indices remain variable and poorly correlated with anesthetic concentration. In older adults, alpha attenuation and spectral flattening elevate pEEG values despite EEG suppression, increasing overdose risk. Age-related EEG differences could influence the interpretation of outcome studies. Although results are mixed, meta-analyses suggest that pEEG-guided or lighter anesthesia may modestly reduce POD incidence but not consistently decrease EA in children. EEG features such as reduced alpha power and increased burst suppression are reliable predictors of POD in adults, while pediatric evidence remains limited. Randomized trials on spectrogram- or raw EEG-guided titration have shown variable neurocognitive outcomes and inconsistent anesthetic-sparing effects. Overall, pEEG reliability declines in both young and older patients. Age-adjusted interpretation-incorporating raw EEG and spectrogram analysis-is essential for accurate anesthetic titration and safer neurocognitive outcomes across the lifespan.